16S rRNA community analysis of oil sands tailings ponds

The purpose of this study was to determine the capacity of indigenous microbes in tailings to degrade bitumen, and if acetate biostimulation further improved degradation. Fluid fine tailings, found in oil sands end-pit lakes (EPL), specifically Base Mine Lake (BML), were used as microbial inocula, and bitumen in the tailings served as a potential carbon source during the experiment. The tailings were capped with 0.22 µm-filtered BML surface water with or without BML bitumen and acetate addition and incubated for 100 days at 20 °C. CO2 production and petroleum hydrocarbon reductions in the tailings were observed. DNA was extracted directly from the tailings, and increased bacterial density was observed by qPCR targeting the rpoB gene in the biostimulated group. 16S rRNA sequencing was used to determine microbial composition profiles in each treatment group. The microbial communities indigenous to the tailings shifted after the bitumen was added. Acidovorax, Rhodoferax, Pseudoxanthomonas and Pseudomonas spp. significantly increased compared to the original microbial community. These may be important hydrocarbon-degraders in an oil sands end pit lake environment, and have demonstrated tolerance to bitumen-based toxicity.